This K23 application proposes a program of patient-oriented research training and studies that will apply novel techniques to investigate the mechanisms of gland proliferation in COPD. The longterm objective is to address persistent gaps in knowledge that prevent the development of novel and specific treatments of gland proliferation in COPD. The proposed approach will apply recently developed techniques for morphometry (design-based stereology), cell isolation (laser capture microdissection), gene expression analysis (two-step real time PCR) and a tissue culture model of gland development. Application of these techniques to bronchial biopsy specimens obtained by bronchoscopy will make it possible to study gene expression in submucosal glands isolated from well characterized human subjects. The specific aims of the proposal are to 1) To determine if submucosal gland proliferation occurs in non-fatal COPD and is associated with serous cell transdifferentiation and MUC5B overexpression. 2)To determine if submucosal gland proliferation in COPD occurs because of new gland growth from the surface epithelium. 3)To determine the role of EGFR and TGFalpha as inducers of submucosal gland proliferation in COPD. We propose two studies: 1) a cross sectional morphologic analysis of airway biopsies from smokers and healthy controls. Using design based stereology we will compare the volume of submucosal glands, the ratio of serous cells to mucous cells in glands, and the volume of MUC5B, TGFalpha and EGFR staining in the glands of smoker's compared to healthy controls. In addition we will quantify the number of terminal collecting ducts per surface area of basal lamina to determine if new gland growth occurs in smokers. 2) an experiment using bronchial biopsies in culture as a model for gland development. Using this model, in combination with morphometry, laser capture microdissection and RT-PCR, we will study the effects of TGFalpha and EGFR on the development of tubuloacinar structures in bronchial biopsy explants. The candidate will complement these studies with a curriculum of advanced training in molecular biology methods of clinical research.